Bug 1378345 - Fix a typo in experiments.rst. r=chutten

MozReview-Commit-ID: Aqsr1gc1Yvh

--HG--
extra : rebase_source : 6135587f365d23cc87f6a3acbb71007cbd6e5b5a

toolkit/components/telemetry/docs/collection/experiments.rst

@@ -37,4 +37,4 @@ Limits and restrictions
 -----------------------
 To prevent abuses, the content of both the experiment ``id`` and ``branch`` is limited to
 100 characters in length.
-``type`` is limited to a lenght of 20 characters.
+``type`` is limited to a length of 20 characters.